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Coax project using Radian 6CRS5130-R ribbon tweeter drivers

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ppataki

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When I was doing my project converting an Adam Audio T5V into a sealed design using fully digital linear phase crossover I got intrigued about how detailed the sound of the ribbon tweeter was....then I did my coax project using Sica 5.5" drivers that did have such a holographic soundstage easily comparable to that of a full range driver.....I said to myself, what if I could combine these two worlds?

After some googling I found out that actually such a thing does exist - a coax driver with a ribbon tweeter!
Enter the Radian 6CRS5130-R


1738939928089.png


I will put these in my sphere cabinets and as usual I will cross them at 80Hz to my subs using digital linear phase crossover (this time probably the new Fabfilter Pro-Q 4)
I have ordered them today, they shall arrive next week
I will then post pictures and also some measurements, stay tuned!
 

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smowry said:
I am also working on a DIY 4-way cardioid loudspeaker project that uses the RADIAN 6CRF 5130. I posted a report on LinkedIn. What are you doing for crossover?

https://www.linkedin.com/pulse/copy-my-retirement-project-part-1-steve-mowry-n848c/?trackingId=BK9XU/GXz2B4rNpUBTDsaQ==

I managed to buy two (2) 6CRF 5130 on Ebay. Radian would not ship to Thailand.
Click to expand...

Wooow! Really interesting project you have there, KUDOS!

smowry said:
What are you doing for crossover?
Click to expand...
As mentioned in my first post, I will be using a linear phase digital crossover (Fabfilter Pro-Q 4) on my PC (which is my source)
The exact crossover frequency will be determined based on measurements, taking into account the distortion curves mainly. Crossover type will be LR 24dB/octave using the linear phase mode of Pro-Q 4
 
My plan is to have the Radian RLC passive network for the 6CRF5130's that I can bypass and switch to miniDSP FLEX HTx. In this way I can select what works best both ways. The FLEX HTx will also conveniently let me try things. I do plan to high pass the 6CRF5130 at 400 -500 Hz with the FLEX HTx. Below that it tends to omni radiation.

Kindly note that my 6CRF5130's had ferrous push terminals for the low frequency transducer. They look good at the end of my magnet pen. Fortunately the lugs were non-ferrous, most likely brass but hopefully copper. I replaced the ferrous push terminals on the 6CRF5130's with M4 copper fish tail lugs soldered to the hookup wires and Nylon fasteners with a bit Loctite 425. I also reperformed (unsolder/solder) the lead dress on 20 other low frequency transducers that had ferrous lugs and push terminals. I replaced the ferrous parts with all copper lugs and M4 Nylon fasteners.
 

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Looks great! It’s a bit of a shame that Radian didn’t use cast frames on that model if even just for aesthetic reasons. All the larger coax they make do, but they don’t have as nice of an advertised response. These would have been my pick too FWIW. Again, best of luck.
 
DanTheMan said:
Looks great! It’s a bit of a shame that Radian didn’t use cast frames on that model if even just for aesthetic reasons. All the larger coax they make do, but they don’t have as nice of an advertised response. These would have been my pick too FWIW. Again, best of luck.
Click to expand...
Radian has two (2) 6-inch models. the 6CRS5130 (round stamped steel frame) and the 6CRF5130 (cast light alloy frame with 4 x ears). All transducer parts seem to be the same except for the frames and the ferrous push connectors on the 6CRF5130. The round frame is easier to mount and this model could be related to ceiling mount applications. The price difference is about US$10 more for the 6CRF5130 model. I found the best place to purchase either the 6CRS5130 or the 6CRF5130 is US Speaker (https://usspeaker-com.3dcartstores.com/Radian_bymfg_6-1-4.html) regardless of the shipping destination. Note made in the Philippines. The 6CRS5130 is US$289.95 and the 6CRF5130 is US$299.95 plus shipping at US Speaker and they will ship with USPS Priority Mail.

​

 
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Karmacoma said:
Oh my god look at this https://radianaudio.com/collections/coaxial-ribbon/products/6crn38lt6-line-array-driver
Very interesting manufacturer.
Click to expand...
Well very interesting company, yes but manufacturer no! Radian is a tiny company with about 12 employees that subcontracts their manufacturing in Asia (https://www.zoominfo.com/pic/radian-audio-engineering-inc/97354619). It took them more than two (2) weeks to reply to a support question. They were busy with the CES et al.
 
smowry said:
Well very interesting company, yes but manufacturer no! Radian is a tiny company with about 12 employees that subcontracts their manufacturing in Asia (https://www.zoominfo.com/pic/radian-audio-engineering-inc/97354619). It took them more than two (2) weeks to reply to a support question. They were busy with the CES et al.
Click to expand...
radianaudio.com

About Radian

Welcome To Sound To The Radian Degree Radian Audio Engineering, Inc., was founded in 1988, with the mission of manufacturing great sounding, high-quality loudspeakers in California, USA. Today, Radian Audio is a major player in the OEM loudspeaker component business, covering all segments of the...
radianaudio.com radianaudio.com
 
The plots suggest quite a lot of beaming above 10kHz.
Is the sphere cabinet ported at the right frequency or closed ?
 
solderdude said:
The plots suggest quite a lot of beaming above 10kHz.
Click to expand...
One wonders if this is a rotational issue? Given that the other Radian planar ribbons have different H and V dispersions, one wonders if that is the same here? The photo that @ppataki made seems to show something circular, though. Quite interesting because there is very little information on these particular planar ribbons. The compression driver and larger planners are much less a mystery. Another thing narrowing the HF response is the 30mm exit diameter of the ribbon throat. A smaller diameter would have improved things here, but these planar diaphragms probably cannot handle a lot of compression, so the exit must be larger.

On the other hand, the purple line is already 30 deg, so it's probably not that big of a deal.

As for the driver, it seems to be of decent enough quality. What I don't like is the stamped steel frame for such a price. I'm sure it will do just fine, but still, I feel like this should be cast aluminum.
 
Last edited:
It is similar to the membrane of the HiVi RT1L and Monacor RBT-56 and round isodynamic drivers used in some headphones.

How these speakers are used the beaming from 10kHz won't be a problem.
In a small sealed enclosure the speakers will roll-off above 100Hz probably starts between 120 and 150Hz or so. Still fine when used with a sub.
When using a high pass filter you can play it a bit louder than when driven full-range.

Time alignment might not be great given how deep the tweeter membrane is but at least it will be constant on each listening position.
Quite expensive drivers though.
 
...and now let's see the measurements!

tldr version: I am not too impressed, especially for this price tag
I have 13 more days to decide if I am going to send them back, will see

All the measurements were taken from the MLP (approx. 250cm from the speakers)

Frequency response

Left woofer and right woofer

1739870908951.png


This looks pretty OK to me, fine until up to 3-4kHz. Bass rolloff is due to the sealed cabinet

Distortion for the woofer

1739871010934.png


Now this was the first thing that made me worry.....
If I apply a low-shelf filter it becomes even worse so it is 'hardware-related distortion'. It is especially bad (worse) with the right speaker
I know I should use these in a ported cabinet but in the last 5 years I have always used all different kinds of drivers in sealed cabinets I have never seen such a big distortion, even my 5.5" Sica is doing a better job here for literally 1/5th of the price.

Frequency response left and right tweeter
1739871361463.png


There is quite a lot of difference there......

Distortion for the tweeter

1739871446621.png


This is actually audible.....
You would not want to cross these low (definitely >2Khz at least)

I have then measured the time delay between the tweeter and the woofer (0.16ms), adjusted volume to match, inverted the tweeter's polarity (response got way better at crossover frequency) and applied linear phase crossover at 4kHz, 24dB/octave, Linkwitz-Riley
And then added my subs as well at 80Hz, same settings as above

Frequency response and phase:

1739871770233.png


I will apply Dirac Live today/tomorrow with some fine tunings but looks fairly good apart from that peak at 10kHz
(remember there is no EQ here, only the crossovers)

Distortion might be an issue, still:

1739871931670.png

In the 100-200Hz region


One interesting thing:
The step response curve totally shows a full range driver, there is no sign of tweeter/woofer temporal separation
I really like that

1739872052653.png


Subjectively:

I would not like to draw any conclusions here yet, I will let the drivers burn in as much as possible in the coming 10 days or so
As mentioned above, I will apply Dirac Live and other tweaks as well

At very first listening they sound pretty good, even with zero EQ (that cannot be said about the Sica drivers, you can't listen to those without EQ)
See a video here about how it sounds without the subwoofers:

photos.app.goo.gl

New video by Peter Pataki

photos.app.goo.gl photos.app.goo.gl

Sound-stage is open and I sense a good level of holography too (will need some more listening to comment better on that)
Treble is already pretty detailed - I guess that will be the forté of these drivers anyway
Big question mark is if distortion will become an issue (especially with movies).....

I will come back in the coming days with more subjective experience and more measurements to share!
 
"Explanation
  • Radian Audio's US-based R&D and manufacturing operations are complemented by affiliate manufacturing resources in the Philippines.

  • Dai-ichi Electronics Manufacturing, a leading audio manufacturer, acquired Radian Audio in 2016.

  • Dai-ichi has five factories in the Philippines and a large factory in Shanghai, China.

  • Dai-ichi supplies speakers and speaker systems to the Philippines and neighboring countries under the Dai-ichi brand and other registered trademarks.

  • Dai-ichi also offers OEM/ODM services to the rest of the world.

  • Dai-ichi has earned the trust of clients such as Sharp, Sony, Panasonic, Samsung, Klipsch, KEF, Celestion, Peavey, and OPPO."
 
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